Swap encryption re-initialisation vs swap shredding

Q1: I have a swap partition that I want to encrypt but I would still like to resume from hibernation. I read there that for increased security, one should reinitialise the encryption frequently (for exemple at each reboot) to make sure no data remains too long. However, I can't find mentions of wipping (replace data) the swap instead of reinitialise the encryption anywhere. Can you find anything about this / what do you think about this ?

Q2: I think it would also be safer to frequently wipe the unused swap space but can it be done with mounted swap ?